normalising music video's

I have a number of various music video's on DVD (which are from various sources: downloads, TV, etc); the annoying thing is that some of these videos don't have the same volume level. Does anyone know of a s/w package which can not only clone the DVD, including retain every .bup, & .ifo file but also keep the existing chapter marks; the only change I want to make is to alter the volume of every video clip.
Nero customer service at first claimed it can do this, but everything resulted in one file without chapter marks.

Due to poor IT knowledge can I please request that any replies don't contain confusing computer jargon. Thanks in advance.